This HMM describes a strictly archaeal putative protein-sorting motif, PGF-CTERM. It is the (predicted) recognition sequence for an exosortase homolog, archaeosortase (TIGR04125). In some archaea, up to fifty proteins have this domain as their C-terminal region, usually preceded by a Thr-rich region likely to be heavily glycosylated. The removal of this sorting signal may be associated with a C-terminal prenyl group modification in the halobacterial major cell surface glycoprotein, an S-layer protein.